Back in 1984, the Association for Computing Machinery presented Ken Thompson with a “Turing Award” for his many contributions to the world of computing.

And for good reason.

Ken worked on Multics, co-created UNIX, created multiple programming languages (Bon and B — which directly led to C), co-created the Plan 9 operating system, UTF-8, and on and on.  If anyone deserves an award for advancing computing... it's Ken Thompson.

But we’re not here today to talk about those extraordinary contributions to computing.

No, sir.

We’re here to talk… about his acceptance speech.

Because that speech revealed a truly fascinatin computer virus that Thompson had created years earlier… for the C compiler.  One which gave him a backdoor into UNIX itself.

The Speech

He titled his speech “Reflections on Trusting Trust”, and the basic premise is this:

“To what extent should one trust a statement that a program is free of Trojan horses? Perhaps it is more important to trust the people who wrote the software.”

To prove his point, Ken told the tale of how he had — years earlier — created what was, essentially, a computer virus that infected the C compiler (cc) and the UNIX login program.

Seriously.

This is real.

Ken could gain control of most UNIX systems

It worked, essentially, like this:

Ken modified cc (the C compiler on UNIX systems) so that — only when it was compiling UNIX’s “login” program — it would inject a small “backdoor” (into “login”) that would allow him to log in as any user on the system if he used a predefined “password”.

Which is, obviously, a pretty big security hole.

However…

That sort of "universall password" code would be likely to be found during even a rudimentary code review of the C compiler. Or, heck, even by any casual programmer who happened upon that section of the code.

What Ken did next was… devious.

Hiding his UNIX backdoor

He needed to make sure that, should anyone find his nefarious code in “cc”… that his backdoor would live on.

So he then added functionality to “cc” so that it would detect if it was compiling itself (because the C compiler was compiled… in the C compiler)… and insert code into the compiler that would add… itself.

Which means…

Even if the source code is removed from “cc” project… the code (for adding both the login backdoor and the “keep adding this to the C compiler” bits) would get “invisibly” injected into “cc” every time it got compiled by an already infected build of the compiler.

So… as long as there was an unbroken chain of using the C compiler from that point onward, the UNIX login backdoor was unlikely to be effectively removed.

Brutal.

According to Thompson:

“The actual bug I planted in the compiler would match code in the UNIX "login" command. The replacement code would miscompile the login command so that it would accept either the intended encrypted password or a particular known password. Thus if this code were installed in binary and the binary were used to compile the login command, I could log into that system as any user.”

The Moral of the story

As Ken Thompson put it…

“The moral is obvious. You can't trust code that you did not totally create yourself. (Especially code from companies that employ people like me.) No amount of source-level verification or scrutiny will protect you from using untrusted code. In demonstrating the possibility of this kind of attack, I picked on the C compiler. I could have picked on any program-handling program such as an assembler, a loader, or even hardware microcode. As the level of program gets lower, these bugs will be harder and harder to detect. A well installed microcode bug will be almost impossible to detect.”

Did this make it out into the wild?

I know what you're thinking.  "Is this code still out there?  How many systems were impacted by this?"

What we know: This bit of naughty code was released to at least one machine (used by a UNIX support group). This has been confirmed by Ken, himself.

However, it is believed that the code went no further than that machine.

But... do we know for sure?

Do we actually have a high level of confidence that the modified “cc” and “login” went no further than that support group UNIX box?

No. No, we do not.

In fact, according to Eric S. Raymond…

“[I have] heard two separate reports that suggest that the crocked login did make it out of Bell Labs, notably to BBN, and that it enabled at least one late-night login across the network by someone using the login name “kt”.”

BBN.  That's Raytheon.  A critical DARPA researcher -- one which was instrumental in the early days of ARPANET.  A huge amount of software came out of BBN.  Heck, even the first Text Adventure game came from there.

If UNIX machines at Raytheon BBN were infected... the possibility of infected versions of those files making it to other sites is incredibly high.

Truly wild

Which leads to a (rather amusing, and mildly terrifying) bit of historical trivia:

Ken Thompson — one of the co-creators of UNIX — intentionally created a trojan horse that infected both the C compiler and the “login” program of UNIX systems.

What’s more… it went undetected for years.  We wouldn't even have known about it, if he hadn't told us he created it.

And we truly have no clue how widespread that trojan became.

Screensaver’s were all the rage in the 1990s. From Flying Toasters to 3D Mazes, screensavers were found on every major operating system across the land.

Screensavers are a fun, and loved, part of the 1990s (and onward) computing experience. But what was the very first one created? What is the story behind the early screensavers? Inquiring minds want to know!

Let’s dive into the glorious early history of… the Screensaver.

The Dreaded Screen Burn-in

Leave any CRT screen (be it a standard television , computer monitor, or even an oscilloscope) on for too long — with the same, non-moving image — and you’ll eventually give your CRT something known as “Burn-in”.

Burn-in is caused by the way CRT’s work: The phosphors which produce the light on the screen tend to lose their luminance over time. Over-use of specific areas will, eventually, cause a dramatic enough change that ghost images can appear.

Screensavers were created to reduce this problem. By making sure that no single portion of the screen could sit, displaying the exact same image, for too long of a period.

1961

The first known reference to something akin to a screensaver is in Robert Heinlein’s Sci-Fi novel, “Stranger in a Strange Land”.

“They went to the living room; Jill sat at his feet and they applied themselves to martinis. Opposite his chair was a stereovision tank disguised as an aquarium; he switched it on, guppies and tetras gave way to the face of the well-known Winchell Augustus Greaves.”

A fish aquarium screensaver (or something very close to it), talked about all the way back in 1961. Pretty cool.

This was, of course, merely a casual reference in a work of fiction. Still… fun to note where Sci-Fi predicts reality.

Many years passed without any actual screensaver being produced. Until…

1977

In 1977, a handful of games for the new Atari Video Computer System (later named the Atari 2600), included simple color cycling effects in order to prevent screen burn-in.

Were these full fledged “screensavers” as we know them nowadays? Not exactly. But they did serve to “save the screen”.

1979

Then, in 1979, Atari released two computer systems: The Atari 400 and 800. Much like the Atari 2600, these Atari computers used a color cycling effect in order to limit screen burn-in. In this case, the effect kicked in after the computer sat idle for a number of minutes.

Not exactly a "Screensaver" -- at least not as we know them today.  But it's the early steps in that direction.

1983

A few years later, in January of 1983, the Apple Lisa (the precursor to the Macintosh) was released. Within it was a system wide Preferences application that allowed the user to set the Lisa to “dim” the display after a definable amount of time.

Note the non-specific amount of time to wait before the screen dims. “I would like the screen to dim between, say, 15 and 30 minutes after I stop using it.”

I find the large time windows highly amusing.  Could the Apple Lisa not handle specific amounts of time?  Fascinating.

Just the same, this is notable as it is the first time an easily configurable “screensaver” like utility is provided on a computer.

Later that same year — in the December, 1983 issue of Softalk Magazine, a young programmer named John Socha published the source code for a small piece of software he dubbed “SCRNSAVE.COM”.

That first PC screensaver was pretty darn simple — it made the screen go blank after an amount of time set in the source code. And, because this was the early 1980’s, you typed the whole thing in by hand from the pages of a magazine.

Want to change how long your computer would wait until the screen went blank? Modify the source code and re-compile.

Side note: Many claim that John Socha’s SCRNSAVE.COM was the first screen saver. Clearly the Apple Lisa shipped first (as did the Atari 400/800). But it very well may be the first screensaver for the IBM PC, which is already a very cool badge of honor. Also worth noting that its author, John Socha (who is also the creator of Norton Commander), would go on to significant things in the screensaver world.

1988

Every attempt at "saving screens", up until now, had been pretty... dull.  Black screens.  Color cycling.  Just enough to pevent screen burn.  That was about to change.

The first publicly released screensaver package which contained distinct, configurable displays… was the “Magic ScreenSaver” for Windows 2.0, first released in 1988 by Bill Stewart and Ian Macdonald as a piece of shareware.

The early versions of Windows did not contain any built-in screensaver functionality. Magic ScreenSaver added that. And it looked like this:

This was it.  Magic ScreenSaver in 1988.  This was the turning point when "Screensavers" became "Screensavers" as we know them today.

1989

Remember how the Apple Lisa had a built-in screen dimming functionality? Strangely, just like early Windows, the Macintosh did not have anything like that.

Enter: After Dark.

Originally developed by James Eastman, After Dark was a screen saver package for the Macintosh. It was initially an un-named hobby project which, after it was shared with a friend at Berkeley Systems, was acquired and renamed “After Dark”.

The first release of After Dark used no bitmap artwork (relying entirely on programmatically generated graphics) and was not anticipated to be a big hit. But it was. And the crew at Berkeley then scrambled to polish it up and release a new version.

1990

Berkeley Systems pushed ahead on adding a new artistic flair to After Dark as they worked on the 2.0 release for Macintosh.

To bring a Windows version to market, they contacted the makers of Magic ScreenSaver to modify and enhance their shareware software… thus morphing it into “After Dark for Windows”.

The 2.0 release brought with it a small pile of new screen saver animations…

But the real breakout hit was “Flying Toasters”.

In a 2007 interview with LowEndMac, the creator of After Dark (James Eastman) recalls the birth of those flying toasters:

“For 2.0 we needed to build more personality into it – really engage. We thought this over in the abstract for quite a while. My wife’s a doctor – she was doing her residency then and was frequently gone overnight. So I’d sit up late programming. Very late.

 

I had a Mac II with a color screen – $5,000 computer in those days.

One of those late nights I was thinking about the artistry problem – how to do something really fun for 2.0.

 

I was wandering around the house. I drifted into the kitchen, and the toaster caught my eye. My sleep-deprived brain put wings on it.

 

I went upstairs and drew some animation frames – I used the development system’s icon editor. Little white outline toasters on a black background with little stubby plucked-chicken wings speed lines and a flapping electrical cord. I coded up the animation that night and brought it to Berkeley Systems the next day.

 

Everybody thought it was hilarious and everybody agreed it needed to be redrawn.

Wes brought in an artist to re-render the toasters, and Patrick re-coded the module in C. The modules all had a little control panel – I insisted on having a slider that controlled the doneness of the toast.”

The result was an instant hit — and an enduring classic.

Which brings us to the end of 1990… the popularity of the screensaver was about to explode.

And, wouldn't you know it, the release of After Dark 2.0 brough with it a Screensaver module named "Aquatic Realm".  A virtual fish tank.

Just like Robert Heinlein wrote about way back in 1961.

From Sci-Fi novel to reality.  Only took us 29 years to get there.

Not too darn shabby.

Between 1980 and 1983, a little company in The Netherlands built the “Holborn” series of computers… which can best be described as “1950s sci-fi… powered by a Z80”.

Note: The “Holborn” name is to signify that these computers were “Born in Holland”.  Hol.  Born.

While the company only lasted for a few years — and they only produced a handful of models — their distinctive designs (for both their cases and their hardware & software choices) are worthy of being remembered.

Just to give you a good example… this is the Holborn 9100 (and connected terminals):

I mean. Wow! Just look at that monitor! That distinctive neck just screams “1950s futurism”… and I absolutely love it.

Ok. Let’s back up a moment.

The company was founded in Hengelo (a town in The Netherlands, near the German border). This is their first office space:

Pictured below are the founders of the company — Dick Gerdzen (left) and Hans Polak (right) — surrounded by a bunch of Holborn computers and terminals.

Now. The computers. Let’s tackle them in chronological order.

The Holborn 9100

The first computer from Holborn was the 9100 (and the accompanying 9120 terminal). Pictured on the left in the picture below.

Note that the 9100 computer portion (where the CPU, drives, etc. were contained) is the size of a mini-fridge or a low profile filing cabinet (with the 9120 terminal sitting on top).

Yeah. The big filing cabinet thing on the floor? That’s the primary computer unit.

The specs of this system were as follows:

• Zilog Z80 CPU @ 3.5 MHz

• 72 KB of RAM (expandable to 220 KB)

• 8 inch floppy drives

Which brings us to the Operating System… it was 100% custom and in-house developed. The Holborn OS was a multi-user system, booted entirely from ROM, which allowed multiple Holborn 9120 terminals to connect to a single Holborn 9100 computer (“Server”).

One extra (and optional) feature of the 9100… it had a photosensitive light pen which could be used as a pointing device. Not a mouse, but a light pen.

What did the Holborn Operating System look like in practice? How did it work? How, exactly, did the light pen work with the included software?

Those are questions I’ve had for many years… yet, despite hunting high and low, have never found so much as a single picture showcasing the Holborn OS in any readable way. Due to the Holborn OS only being available in ROM on the 9100 itself… no known digital archival copy exists.

In the end, only roughly 200 Holborn 9100 units were sold. (Though that number is debated… more on that in a moment.)

The Holborn 7100

This was a simplified (and cheaper) version of the 9100. Instead of supporting a whole office worth of connected terminals (as with the 9100), the 7100 only supported two connected terminals (users) at once.

It looked like the 9100. Acted like the 9100. Just with… less.

It is unknown how well this model sold. It is assumed that it did not sell well.

The Holborn 6100

In 1982, the Holborn Computer company had to make some tough decisions.

Their Holborn OS (booted from ROM), was not proving popular. And the CP/M operating system (from Gary Kildall’s Digital Research in Pacific Grove, California) was rapidly gaining in popularity.

Luckily the architecture already in use by Holborn computers (the Z80) had a native version of CP/M.

Thus the lower priced, and smaller footprint, Holborn 6100 line was born. Same Z80 CPU, and now with a maximum 192 KB of RAM (slightly less than the 9100)… but, this time, booting the CP/M operating system off disk.

No more booting from ROM. No more in-house developed operating system.

This is the Holborn 6140 with the connected 6110 terminal. See? Much smaller than that gigantic 9100 mini-fridge. But still retained that fantastically interesting terminal design.

Here is a shot of the Holborn 6100’s screen, running CP/M.

How many of these machines shipped? Reports put it somewhere in the ballpark of around 100.  Total.

Though the lack of information makes this fact difficult to confirm. Regardless, it was not exactly selling like hotcakes.

The Holborn 6500

The final computer designed by Holborn was the ill-fated 6500.

In the 6500, Holborn removed the keyboard from the terminal body (making it a detached keyboard), and filled the base of the terminal with the computer guts (thus eliminating the need for the separate computer housing used in earlier models). As shown in this advertisement for the “not yet released” 6500:

And here is a shot of the inside of the Holborn 6500, with the top of the case lifted up to show the internals.

Unfortunately Holborn Computers declared bankruptcy in April of 1983… before shipping the 6500.

The End of Holborn

And here is where things become increasingly sad for the company.

When Holborn went bankrupt, investigators determined that only 50 units were sold of the 9100 and 7100 combined. And that the company had over 3.5 million guilders in debt. (Guilders were the currency in use in The Netherlands prior to changing to the Euro. Some quick math tells us that 3.5 Million guilders would be roughly equal to $7 Million USD.)

Would the 6500 model have been enough to save the company? Who knows. Considering the poor sales up till then, and the relatively massive debt (when compared to sales), it seems unlikely.

But one thing is for certain… those are some seriously funky (and awesome) looking machines. So I’m sure glad they tried.

If you ever run across a Holborn, count yourself lucky.  These are some of the hardest computers to find nowadays. Considering that only a few hundred were ever sold, you aren’t likely to stumble across them at a flea market or eBay.

With that, I leave you with some pictures of Holborn computers in action.  Because they're just so darned cool looking.